Carl wrote:
> Trying to decipher Orr at times is a task.
>
> Is he trying to say that the tube absorbs 90% and feed thru 10%?
>
If true that only 10% is fed through it would make the old FCC reg about
adding the driving power to the output a bit strange as it seems as I
recall we were expected to add the driving power to the input power of
the amp when computing the legal 1KW DC input, or 2 KW PEP.
As the driving power goes into the cathode which is in phase with the
plate power output, I'd expect the majority of that power to show up
minus perhaps the grid power or am I looking at that wrong?
73
Roger (K8RI)
> If so wouldnt loading for optimum grid current in the spec sheet accomplish
> that? Sort of by default?
>
> Ive never read that version, which edition were you reading?
>
> Carl
> KM1H
>
>
>
> ----- Original Message -----
> From: <TexasRF@aol.com>
> To: <amps@contesting.com>
> Sent: Tuesday, March 30, 2010 7:13 PM
> Subject: [Amps] gg feed through power
>
>
>
>> After more reading in the Orr book, I discovered a discussion of feed
>> through power in a cathode driven amplifier.
>>
>> We have all heard about the drive power adding to the output power. Orr
>> says, and I am paraphrasing here, that a PORTION of the drive power is
>> added
>> to the output power. He goes on to say that the greater the ratio of
>> drive
>> power to the feed through power, the better the imd performance. He
>> further
>> suggested that the optimum feed through power for best imd performance is
>> about 10%.
>>
>> Heck, 10% of a 100w drive level is insignificant and might as well be
>> ignored.
>>
>> He did not describe how one goes about attaining the 10% feed through
>> level
>> and I suspect there is no control of this. Perhaps you get what you get
>> with a given tube?
>>
>> He also wrote about the improved imd performance due to the heavy negative
>> feed back inherent in cathode driven amplifiers compared to grid driven;
>> often in the 10 to 15 dB range of improvement.
>>
>> We have always heard this to be so; at least that old saying is correct.
>>
>> 73,
>> Gerald K5GW
>>
>>
>>
>>
>>
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>>
>
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